This invention relates to compasses, and more particularly relates to a novel and improved compass which is extremely versatile, user-friendly and accurate.
I have previously devised a recreational compass of the type having an inner vial including a compass needle and azimuth ring which is yieldingly mounted in a housing, reference being made to U.S. Pat. No. 4,438,568 assigned to The Brunton Company of Riverton, Wyo., the assignee of this invention. This invention is directed to certain improvements to produce more accurate results and readability of azimuth bearing, inclination angles and declination settings together with a novel and improved needle alignment system in a compact, compass design which can be positioned in a protective shoe and in such a way as to enable the use of a compass for most operations without removal from the shoe.
It is therefore an object of the present invention to provide for a novel and improved compass of the type designed for outdoor and recreational purposes.
It is another object to provide for a novel and improved means for assembling a compass vial onto a base without positive attachment and in such a way that the vial can be positively rotated to a desired position but is not subject to accidental movement or rotation.
It is still another object of the present invention to provide for a shoe which forms a protective cover and provides a tactile grip when using the compass for retention of the base of the compass as well as for storage of various scales and instructional cards and wherein the shoe will enable efficient use of the compass without removal from the shoe.
Among other advantages and features of the present invention is a needle alignment system in which the compass is made up of a vial or capsule containing a magnet of molded plastic with magnetic particles embedded therein, a circle on the vial and a transparent disk mounted on the magnet which has a smaller diameter circle printed on it in the same radial location as the printed circle on the vial. Accordingly, alignment is achieved in a bull""s eye fashion with a concentric gap formed between the rings when in perfect alignment and which also serves as an optical level for the compass when viewed through a mirrored cover which is employed in cooperation with the compass vial assembly.
Another desirable feature is that the center compass vial assembly is allowed to move independently within the outer grip ring to set declination of magnetic North, an arrow being printed on the back side of the center vial which is the North indicator and allows non-parallax adjustment of less than 1xc2x0. This same adjustment feature can be employed to preset the vial assembly to take inclinometer readings off of the scale on the compass vial when the compass is placed on one of its side edges in reading up or down inclinations. Still further, a pendulum inclinometer is located within the vial having a clear film pendulum with a printed center arrow of contrasting color as compared to the background of a card retained in the shoe to indicate tilt, or a given vertical angle. Typically, this card may be graduated in 5xc2x0 increments for a total of 180xc2x0 and is one of several cards stored in the relief area within the shoe.
As still another feature of the present invention, an azimuth ring is united to the compass vial and aids in assembly of the compass vial to the base and includes bearing as well as back bearing markings which can be read through a magnifier on the base, the magnifier being designed with an index line on its underside to eliminate parallax error and magnify the azimuth scale for increased accuracy.
A novel and improved dual cover assembly includes a pair of covers hinged about a common hinge pin(s) in such a way that the covers can be moved to selected positions independently or together. When in the closed position directly over the vial and base assembly, the inner sight cover can be raised to expose the vial assembly, and the grip ring is readily accessible through opposite sides of the cover without removing the cover away from the base. In addition, the cover includes an angle finder or protractor at its hinge area which is graduated in selected increments so that readings can be taken at an index point on the hinge as an indication of the angle formed between the base and cover.
The foregoing is given more for the purpose of illustration and not limitation with respect to different features of the compass.
The above and other objects, advantages and features of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of preferred and modified forms of the present invention when taken together with the accompanying drawings in which: